There have been extensive advancements over the past fifteen years in terms of surgical reconstruction of the anterior cruciate ligament deficient knee. Not only have the technics for repair and/or reconstruction evolved but so have the selection of materials utilized in these surgical procedures. There are a variety of materials, such as heterografts, allografts, autografts and synthetics, that have been used. This natural evolutionary process is by no means final, however it has become clear that there is an obvious prediliction for the use of biological tissue when it comes to making the selection for the most appropriate material for ACL reconstruction. In concert with this evolutionary process has been a greater awareness and understanding in regards to the natural history of this particular injury pattern as well as a more aggressive approach to post surgical rehabilitation. Of tantamount inportance during this learning period has been an acute appreciation in the necessity for surgical precision and reduced patient morbidity.
Without adequate emphasis directed toward precise surgical detail, even the most appropriately selected material will be fraught with a host of potential problems including; flexion contractures, patello-femoral pain, loss of range of motion, and frank failure of the reconstruction with resultant instability. The secondary restraints of the knee, as well as the menisci, are further jeopardized with the return to the previous level of instability. It goes without saying that technical surgical precision is fundamentally important for the successful outcome of the surgical procedure. This in fact is borne out by the dramatic growth in the surgical instrumentation market, as well as the advancements developed with arthroscopic techniques. One feature which has enhanced the accuracy of the surgical procedure has been the utilization of drill guides to aid in the precision of bone tunnel placement in the proximal tibia and distal femur. There are no less than two dozen drill guides that have been developed over the past two decades which are intended to provide increased accuracy of bone tunnel placement; some to a lesser or greater degree.
It is not the intent of this application to address all of the different drill guide concepts that have been reviewed for the purpose of this application but to address only those which embody similar ideas as embodied in the scope of this application. As with most drill guides utilized in cruciate ligament reconstructive procedures, the primary intent is to place a through-and-through tunnel in the proximal tibia originating externally on the tibial cortex just medial to the tibial tuberosity and exiting at the pre-selected anatomic insertion site of the ACL on the tibial plateau. Some guides have an additional modification of the tibial component which is then utilized to create the femoral tunnel. There are many variations of the method to create the femoral tunnel which include; anatomic versus over-the-top, through-and-through tunnel versus blind femoral tunnel, accessing the tunnel externally and exiting intra-articularly versus accessing the tunnel intra-articularly on the anatomic origin of the ACL. Most often the axes of the femoral and tibial tunnels are placed independent of one another. Those drill guides which index from the axis of one tunnel to create the axis of the second tunnel will be discussed here as that is one of the critical factors within the scope of this application.
Currently there are five drill guide concepts which embody the concept of attempting to achieve alignment of the tibial and femoral bone tunnels such that they follow a single axis or at least attempt to achieve alignment in a single plane. For example, secondary placement of the femoral tunnel can be indexed from the preplaced tibial tunnel such that the axes of both tunnels lies in a straight line (at a given knee flexion usually around ninety degrees) or that the axes of the two tunnels lie in the same plane relative to the flexion and extension of the knee. Those five drill guides which share these concepts include the following patents or product literature: Goble U.S. Pat. No. 4,772,286 & 4,901,711!, Laboureau U.S. Pat. No. 5,112,335!, Bolton U.S. Pat. No. 4,945,904!, Hendler Uni-Tunnel Drill Guide System Manufacturerd by Richard Wolf Medical Instruments! and Isometric Drill Guide Manufactured by Stryker!. Patents by Goble discuss details for placement of bony tunnels through the tibia and femur. In particular, U.S. Pat. No. 4,901,711 illustrates a drill guide that mounts to a preplaced K-wire fitted through a straight bone tunnel incorporating the attachment sites of the ACL. During the description for placement of the K-wire he describes the need of the surgeon to observe the placement by means of fluoroscopic and arthroscopic monitoring while the knee is maintained in approximately ninety degrees of flexion. While this technique provides for a straight tibio-femoral bone tunnel it is difficult at best to be certain that the bone tunnel will pass through the exact attachment sites of the ACL. Although Goble describes in his patent that while under fluoroscopic and arthroscopic control the guidewire can be driven through the tibia and across the cruciate ligament junctions with the proximal tibia and distal femur ends and into the femoral cortex, one can not be certain to accurately intersect the anatomic sites with the guidewire by starting the drilling at the external tibial cortex. Only through trial and error and repeated passes of the guidewire can one hope to properly position the guidewire such that it will create a straight path from the external tibial cortex through the tibial metaphysis entering the joint space at the anatomic insertion site of the ACL and then penetrating the femur at precisely the anatomic origin of the ACL. This of course can only be achieved with the knee maintained at approximately ninety degrees of flexion. In addition this method requires the use of fluoroscopy with its attendant expense, space-occuping problems in the operating room, radiation exposure hazards and along with the requisite skill necessary to use the equipment properly and to accurately interpret the image.
Other drill guide systems such as the Hendler Uni-Tunnel Drill Guide and the Isometric Drill Guide make mention of trying to achieve a straight tibio-femoral bone tunnel which passes through the anatomic origin and insertion sites of the ACL. The Hendler Uni-Tunnel system illustrates a drill guide system which allows for placement of a straight tibio-femoral bone tunnel alignment, however the intra-articular aiming device, while it can help to stabilize the guide pin as it passes through the joint space, can not accurately direct the guide pin to intersect precisely the anatomic sites of origin and insertion of the ACL. The intra-articular aiming device may be able to direct the guide pin to intersect either the femoral or tibial insertion site of the ACL but it is not able to simultaneously direct the guide pin to intersect both of the anatomic sites. Although this system can be utilized in conjunction with arthroscopic monitoring, it does require a femoral cut down procedure in order to position the femoral post against the lateral femoral cortex. Similar to the Hendler Uni-Tunnel system, the Isometric Drill Guide is intended to provide a straight tibio-femoral bone tunnel also while the knee is held in approximately ninety degrees of flexion. The Isometric Drill Guide requires an arthrotomy incision in order to introduce the relatively large aiming portion into the knee joint. The design of this drill guide system is such that the intra-articular portion of the guide is used to identify the attachment site on the tibial plateau, however it can not accurately identify the attachment site on the femur. Therefore, it is only by trial and error that placement of the guide pin will intersect the femoral anatomic site of the ACL. It also requires direct observation through the arthrotomy incision or by the aid of radiography in order to facilitate placement of the guide pin.
While Laboureau and Bolton describe drill guide systems that provide for placement of the tibial and femoral bone tunnels to be in the same plane; they do not allow for placement along a single straight axis. Laboureau goes on to claim that with his technique he can obtain an alignment of marking and drilling directions of the femur and tibial insertion tunnels when the knee is in extension. However, given the geometry of the knee joint it is not possible to obtain a straight tibio-femoral tunnel intersecting the anatomic sites of the ACL when the knee is in or near full extension. He further goes on to claim that with the knee in the extension position the prolongation of the femoral insertion tunnel is almost in the axis of the tibial insertion tunnel. Similar to the patent by Bolton, both of these drill guide designs result in the placement of the tibial and femoral bone tunnels in the same plane but certainly not along a single axis. Although in the patent described by Bolton the technique does allow for the axis of the tibial tunnel and the intraarticular segment to be in a straight line near full extension of the knee. However, the axis of the femoral tunnel relative to the axis of the tibial tunnel can only achieve the relationship of being in the same plane. Also, the drill guide systems of Laboureau and Bolton require a femoral cut down procedure and a through-and-through femoral bone tunnel, in addition the technique as described by Laboureau requires the use of teleradiography in order to properly locate the anatomic site of origin of the ACL.
The previously mentioned drill guide systems are intended to achieve a tibio-femoral bone tunnel relationship in which the alignment of the central axes of the two independent tunnels is in a straight line or in the same plane in regards to flexion and extension of the knee. While this may be the intention of the formerly described systems it is also apparent that they are not capable of providing an accurate, repeatedly reproducible, straight tibio-femoral bone tunnel which intersects the anatomic origin and insertion of the ACL. The achievement of this often sought after straight tibio-femoral bone tunnel configuration can be obtained, however generally only after trial and error with repeated passes of the guide pin. The only means by which to accurately and repeatably place the guide pin in a straight line intersecting the anatomic sites of the ACL is by means of a specially designed drill guide as described in this application. The direction today in terms of innovative development in surgical instrumentation is focused on several goals; precision, accuracy and repeatability, user friendly, simple and easy to use, reduction of patient morbidity, saves time, facilitation of the procedure for the surgeon, cost effective, minimally invasive, and nondisposable.